Billy Halleck commits vehicular homicide when his lack of attention to driving results in the death of an old lady on the street. Overweight Halleck is a lawyer with connections, though, and gets off with a slap on the wrist. After his trial, a gypsy curses him with a single word, "Thinner." Halleck begins to lose weight uncontrollably and must pursue the band of gypsies who are responsible for his dwindling condition.